Portable electronic devices, such as cellular phones, laptop computers, and other consumer products typically include a replaceable and rechargeable battery pack. When one battery pack is depleted, it can be removed and replaced with another fully charged battery pack while the depleted battery pack is recharged. A battery pack typically includes a sealed enclosure which contains rechargeable batteries. Contacts on the exterior surface of the battery pack mate with contacts on the electronic device when the battery pack is mounted to the electronic device. Battery packs typically have exterior surfaces which blend with the contours of the electronic device in an aesthetically pleasing way and latch mechanisms which are relatively unobtrusive but easy to use.
There are many types of latching mechanisms for use in battery packs. One of the most common types of mechanisms is a simple plastic cantilever latch. This type of latch comprises a cantilever or beam which is anchored at one end and carries a latch element at the opposite end. The cantilever or beam is deflected in order to engage or disengage the latch. In general, long cantilevers are preferred over short cantilevers for several reasons. First, longer cantilevers allow for greater deflection which in turn allows for greater latch engagement. Moreover, in order to make the plastic cantilevers strong, it is often necessary to make them thick. Thick cantilevers require greater effort than thin beams to deflect. If low efforts are desired, then the cantilever must be made thinner or longer. It is difficult to design long cantilevers into the product, and thin cantilevers are weak.
An alternative to cantilever latches, are spring-loaded cam latches. In this type of latch, a metal leaf spring or coil spring is used to urge a latch member to an engaged position. The latch member often includes a camming surface which is engaged by an actuator element to move the latch member to a disengaged position. Spring-loaded latches have several advantages over cantilever latches. The metal springs provide a smoother, almost constant latch effort. It is easier to design latch mechanisms with the desired latch force, travel and feel without the trade-offs of cantilever latches. The space requirements for spring-loaded latching mechanisms is often less than cantilever latches, which is important as electronic devices become smaller and more portable.
Despite the many advantages of spring-loaded latching devices, there are difficulties with this design as well. The primary drawback with spring-loaded latch mechanisms is that they are typically difficult and usually more costly to assemble. The springs must be held in a loaded condition during assembly. Often times, the size or placement of the springs make them difficult to handle and place properly. Also, it is difficult to hold the components in a stationary position during assembly because of the components are designed for relative movement with respect to one another. These problems make assembly of spring-loaded latch mechanisms more difficult and more costly.
Accordingly, there is a need for a small, unobtrusive latch mechanism which is reliable and easy to activate while still being cost effective and easy to manufacture.